New research suggests prejudices may form at a much earlier age, but it also offers hope that biases can be unlearned

For more than four decades, the notion that racism and physical prejudice don’t fully develop in humans until the teen or adult years has been at the root of research into racism. Popular scientific belief had been that children, who only develop the ability to express racial preferences at around age 3, gradually develop those preferences over time and only cement them well into their teen years.

But new research not yet published by Mahzarin Banaji, a renowned Harvard University psychologist, brain researcher, and racism and physical prejudice expert, and colleagues suggests that even though they may not understand the “why’’ of their feelings, children exposed to racism tend to accept and embrace it as young as age 3, and in just a matter of days.